Square of lower triangular normalized 2nd kind Stirling matrix.

Terms

a(0) =1a(1) =3a(2) =1a(3) =27a(4) =21a(5) =2a(6) =173a(7) =227a(8) =48a(9) =2a(10) =2213a(11) =4283a(12) =1479a(13) =134a(14) =3a(15) =1239065a(16) =3303383a(17) =1635807a(18) =238718a(19) =11475a(20) =156a(21) =1178661599a(22) =4156965497a(23) =2749126434a(24) =569141150a(25) =43679400a(26) =1263600a(27) =11310a(28) =537440137205